Designation: E94 – 04 (Reapproved 2010)
Standard Guide for
Radiographic Examination1
This standard is issued under the fixed designation E94; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide2 covers satisfactory X-ray and gamma-ray
radiographic examination as applied to industrial radiographic
film recording. It includes statements about preferred practice
without discussing the technical background which justifies the
preference. A bibliography of several textbooks and standard
documents of other societies is included for additional information on the subject.
1.2 This guide covers types of materials to be examined;
radiographic examination techniques and production methods;
radiographic film selection, processing, viewing, and storage;
maintenance of inspection records; and a list of available
reference radiograph documents.
NOTE 1—Further information is contained in Guide E999, Practice
E1025, Test Methods E1030, and E1032.
1.3 Interpretation
and
Acceptance
Standards—
Interpretation and acceptance standards are not covered by this
guide, beyond listing the available reference radiograph documents for castings and welds. Designation of accept - reject
standards is recognized to be within the cognizance of product
specifications and generally a matter of contractual agreement
between producer and purchaser.
1.4 Safety Practices—Problems of personnel protection
against X rays and gamma rays are not covered by this
document. For information on this important aspect of radiography, reference should be made to the current document of the
National Committee on Radiation Protection and Measurement, Federal Register, U.S. Energy Research and Development Administration, National Bureau of Standards, and to
state and local regulations, if such exist. For specific radiation
safety information refer to NIST Handbook ANSI 43.3, 21
CFR 1020.40, and 29 CFR 1910.1096 or state regulations for
agreement states.
1.5 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro1
This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.01 on Radiology
(X and Gamma) Method.
Current edition approved June 1, 2010. Published November 2010. Originally
approved in 1952. Last previous edition approved in 2004 as E94 - 04. DOI:
10.1520/E0094-04R10.
2
For ASME Boiler and Pressure Vessel Code applications see related Guide
SE-94 in Section V of that Code.
priate safety and health practices and determine the applicability of regulatory limitations prior to use. (See 1.4.)
1.6 If an NDT agency is used, the agency shall be qualified
in accordance with Practice E543.
2. Referenced Documents
2.1 ASTM Standards:3
E543 Specification for Agencies Performing Nondestructive Testing
E746 Practice for Determining Relative Image Quality
Response of Industrial Radiographic Imaging Systems
E747 Practice for Design, Manufacture and Material
Grouping Classification of Wire Image Quality Indicators
(IQI) Used for Radiology
E801 Practice for Controlling Quality of Radiological Examination of Electronic Devices
E999 Guide for Controlling the Quality of Industrial Radiographic Film Processing
E1025 Practice for Design, Manufacture, and Material
Grouping Classification of Hole-Type Image Quality Indicators (IQI) Used for Radiology
E1030 Test Method for Radiographic Examination of Metallic Castings
E1032 Test Method for Radiographic Examination of Weldments
E1079 Practice for Calibration of Transmission Densitometers
E1254 Guide for Storage of Radiographs and Unexposed
Industrial Radiographic Films
E1316 Terminology for Nondestructive Examinations
E1390 Specification for Illuminators Used for Viewing
Industrial Radiographs
E1735 Test Method for Determining Relative Image Quality of Industrial Radiographic Film Exposed to
X-Radiation from 4 to 25 MeV
E1742 Practice for Radiographic Examination
E1815 Test Method for Classification of Film Systems for
Industrial Radiography
2.2 ANSI Standards:
PH1.41 Specifications for Photographic Film for Archival
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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E94 – 04 (2010)
Records, Silver-Gelatin Type, on Polyester Base4
PH2.22 Methods for Determining Safety Times of Photographic Darkroom Illumination4
PH4.8 Methylene Blue Method for Measuring Thiosulfate
and Silver Densitometric Method for Measuring Residual
Chemicals in Films, Plates, and Papers4
T9.1 Imaging Media (Film)—Silver-Gelatin Type Specifications for Stability4
T9.2 Imaging Media—Photographic Process Film Plate and
Paper Filing Enclosures and Storage Containers4
2.3 Federal Standards:
Title 21, Code of Federal Regulations (CFR) 1020.40,
Safety Requirements of Cabinet X-Ray Systems5
Title 29, Code of Federal Regulations (CFR) 1910.96,
Ionizing Radiation (X-Rays, RF, etc.)5
2.4 Other Document:
NBS Handbook ANSI N43.3 General Radiation Safety
Installations Using NonMedical X-Ray and Sealed
Gamma Sources up to 10 MeV6
3. Terminology
3.1 Definitions—For definitions of terms used in this guide,
refer to Terminology E1316.
4. Significance and Use
4.1 Within the present state of the radiographic art, this
guide is generally applicable to available materials, processes,
and techniques where industrial radiographic films are used as
the recording media.
4.2 Limitations—This guide does not take into consideration special benefits and limitations resulting from the use of
nonfilm recording media or readouts such as paper, tapes,
xeroradiography, fluoroscopy, and electronic image intensification devices. Although reference is made to documents that
may be used in the identification and grading, where applicable, of representative discontinuities in common metal castings and welds, no attempt has been made to set standards of
acceptance for any material or production process. Radiography will be consistent in sensitivity and resolution only if the
effect of all details of techniques, such as geometry, film,
filtration, viewing, etc., is obtained and maintained.
5. Quality of Radiographs
5.1 To obtain quality radiographs, it is necessary to consider
as a minimum the following list of items. Detailed information
on each item is further described in this guide.
5.1.1 Radiation source (X-ray or gamma),
5.1.2 Voltage selection (X-ray),
5.1.3 Source size (X-ray or gamma),
5.1.4 Ways and means to eliminate scattered radiation,
5.1.5 Film system class,
5.1.6 Source to film distance,
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036.
5
Available from U.S. Government Printing Office Superintendent of Documents,
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.
6
Available from National Technical Information Service (NTIS), U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161.
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5.1.7 Image quality indicators (IQI’s),
5.1.8 Screens and filters,
5.1.9 Geometry of part or component configuration,
5.1.10 Identification and location markers, and
5.1.11 Radiographic quality level.
6. Radiographic Quality Level
6.1 Information on the design and manufacture of image
quality indicators (IQI’s) can be found in Practices E747,
E801, E1025, and E1742.
6.2 The quality level usually required for radiography is
2 % (2-2T when using hole type IQI) unless a higher or lower
quality is agreed upon between the purchaser and the supplier.
At the 2 % subject contrast level, three quality levels of
inspection, 2-1T, 2-2T, and 2-4T, are available through the
design and application of the IQI (Practice E1025, Table 1).
Other levels of inspection are available in Practice E1025 Table
1. The level of inspection specified should be based on the
service requirements of the product. Great care should be taken
in specifying quality levels 2-1T, 1-1T, and 1-2T by first
determining that these quality levels can be maintained in
production radiography.
NOTE 2—The first number of the quality level designation refers to IQI
thickness expressed as a percentage of specimen thickness; the second
number refers to the diameter of the IQI hole that must be visible on the
radiograph, expressed as a multiple of penetrameter thickness, T.
6.3 If IQI’s of material radiographically similar to that being
examined are not available, IQI’s of the required dimensions
but of a lower-absorption material may be used.
6.4 The quality level required using wire IQI’s shall be
equivalent to the 2-2T level of Practice E1025 unless a higher
or lower quality level is agreed upon between purchaser and
supplier. Table 4 of Practice E747 gives a list of various
hole-type IQI’s and the diameter of the wires of corresponding
EPS with the applicable 1T, 2T, and 4T holes in the plaque IQI.
Appendix X1 of Practice E747 gives the equation for calculating other equivalencies, if needed.
7. Energy Selection
7.1 X-ray energy affects image quality. In general, the lower
the energy of the source utilized the higher the achievable
radiographic contrast, however, other variables such as geometry and scatter conditions may override the potential advantage of higher contrast. For a particular energy, a range of
thicknesses which are a multiple of the half value layer, may be
radiographed to an acceptable quality level utilizing a particular X-ray machine or gamma ray source. In all cases the
specified IQI (penetrameter) quality level must be shown on
the radiograph. In general, satisfactory results can normally be
obtained for X-ray energies between 100 kV to 500 kV in a
range between 2.5 to 10 half value layers (HVL) of material
thickness (see Table 1). This range may be extended by as
much as a factor of 2 in some situations for X-ray energies in
the 1 to 25 MV range primarily because of reduced scatter.
8. Radiographic Equivalence Factors
8.1 The radiographic equivalence factor of a material is that
factor by which the thickness of the material must be multiplied to give the thickness of a “standard” material (often steel)
E94 – 04 (2010)
TABLE 1 Typical Steel HVL Thickness in Inches (mm) for
Common Energies
Thickness,
Inches (mm)
Energy
120 kV
150 kV
200 kV
250 kV
400 kV (Ir 192)
1 MV
2 MV (Co 60)
4 MV
6 MV
10 MV
16 MV and higher
0.10
0.14
0.20
0.25
0.35
0.57
0.80
1.00
1.15
1.25
1.30
(2.5)
(3.6)
(5.1)
(6.4)
(8.9)
(14.5)
(20.3)
(25.4)
(29.2)
(31.8)
(33.0)
which has the same absorption. Radiographic equivalence
factors of several of the more common metals are given in
Table 2, with steel arbitrarily assigned a factor of 1.0. The
factors may be used:
8.1.1 To determine the practical thickness limits for radiation sources for materials other than steel, and
8.1.2 To determine exposure factors for one metal from
exposure techniques for other metals.
9. Film
9.1 Various industrial radiographic film are available to
meet the needs of production radiographic work. However,
definite rules on the selection of film are difficult to formulate
because the choice depends on individual user requirements.
Some user requirements are as follows: radiographic quality
levels, exposure times, and various cost factors. Several
methods are available for assessing image quality levels (see
Test Method E746, and Practices E747 and E801). Information
about specific products can be obtained from the manufacturers.
9.2 Various industrial radiographic films are manufactured
to meet quality level and production needs. Test Method E1815
provides a method for film manufacturer classification of film
systems. A film system consist of the film and associated film
processing system. Users may obtain a classification table from
the film manufacturer for the film system used in production
radiography. A choice of film class can be made as provided in
Test Method E1815. Additional specific details regarding
classification of film systems is provided in Test Method
E1815. ANSI Standards PH1.41, PH4.8, T9.1, and T9.2 provide specific details and requirements for film manufacturing.
10. Filters
10.1 Definition—Filters are uniform layers of material
placed between the radiation source and the film.
10.2 Purpose—The purpose of filters is to absorb the softer
components of the primary radiation, thus resulting in one or
several of the following practical advantages:
10.2.1 Decreasing scattered radiation, thus increasing contrast.
10.2.2 Decreasing undercutting, thus increasing contrast.
10.2.3 Decreasing contrast of parts of varying thickness.
10.3 Location—Usually the filter will be placed in one of
the following two locations:
10.3.1 As close as possible to the radiation source, which
minimizes the size of the filter and also the contribution of the
filter itself to scattered radiation to the film.
10.3.2 Between the specimen and the film in order to absorb
preferentially the scattered radiation from the specimen. It
should be noted that lead foil and other metallic screens (see
13.1) fulfill this function.
10.4 Thickness and Filter Material— The thickness and
material of the filter will vary depending upon the following:
10.4.1 The material radiographed.
10.4.2 Thickness of the material radiographed.
10.4.3 Variation of thickness of the material radiographed.
10.4.4 Energy spectrum of the radiation used.
10.4.5 The improvement desired (increasing or decreasing
contrast). Filter thickness and material can be calculated or
determined empirically.
11. Masking
11.1 Masking or blocking (surrounding specimens or covering thin sections with an absorptive material) is helpful in
reducing scattered radiation. Such a material can also be used
to equalize the absorption of different sections, but the loss of
detail may be high in the thinner sections.
12. Back-Scatter Protection
12.1 Effects of back-scattered radiation can be reduced by
confining the radiation beam to the smallest practical cross
TABLE 2 Approximate Radiographic Equivalence Factors for Several Metals (Relative to Steel)
Energy Level
Metal
Magnesium
Aluminum
Aluminum alloy
Titanium
Iron/all steels
Copper
Zinc
Brass
Inconel X
Monel
Zirconium
Lead
Hafnium
Uranium
100 kV
150 kV
220 kV
0.05
0.08
0.10
0.05
0.12
0.14
0.54
1.0
1.6
1.4
1.4
1.4
0.08
0.18
0.18
0.54
1.0
1.4
1.3
1.3
1.3
1.2
2.0
12.0
14.0
20.0
1.0
1.5
1.7
2.4
14.0
2.3
14.0
250 kV
400 kV
1 MV
2 MV
4 to 25 MV
192
Ir
60
Co
0.35
0.35
0.9
1.0
1.1
1.1
1.1
1.3
0.35
0.35
0.9
1.0
1.1
1.0
1.0
1.3
0.71
1.0
1.4
1.3
1.3
1.3
0.9
1.0
1.1
0.9
1.0
1.1
1.2
1.3
1.1
1.3
0.9
1.0
1.2
1.2
1.0
1.3
1.7
1.5
1.0
2.5
1.0
2.7
1.2
4.0
1.0
2.3
12.0
16.0
9.0
12.0
1.0
5.0
3.0
4.0
3.9
12.6
3.4
1.0
1.4
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13. Screens
13.2.3 Gold, tantalum, or other heavy metal screens may be
used in cases where lead cannot be used.
13.3 Fluorescent Screens—Fluorescent screens may be
used as required providing the required image quality is
achieved. Proper selection of the fluorescent screen is required
to minimize image unsharpness. Technical information about
specific fluorescent screen products can be obtained from the
manufacturers. Good film-screen contact and screen cleanliness are required for successful use of fluorescent screens.
Additional information on the use of fluorescent screens is
provided in Appendix X1.
13.4 Screen Care—All screens should be handled carefully
to avoid dents and scratches, dirt, or grease on active surfaces.
Grease and lint may be removed from lead screens with a
solvent. Fluorescent screens should be cleaned in accordance
with the recommendations of the manufacturer. Screens showing evidence of physical damage should be discarded.
13.1 Metallic Foil Screens:
13.1.1 Lead foil screens are commonly used in direct
contact with the films, and, depending upon their thickness,
and composition of the specimen material, will exhibit an
intensifying action at as low as 90 kV. In addition, any screen
used in front of the film acts as a filter (Section 10) to
preferentially absorb scattered radiation arising from the specimen, thus improving radiographic quality. The selection of lead
screen thickness, or for that matter, any metallic screen
thickness, is subject to the same considerations as outlined in
10.4. Lead screens lessen the scatter reaching the film regardless of whether the screens permit a decrease or necessitate an
increase in the radiographic exposure. To avoid image unsharpness due to screens, there should be intimate contact between
the lead screen and the film during exposure.
13.1.2 Lead foil screens of appropriate thickness should be
used whenever they improve radiographic quality or penetrameter sensitivity or both. The thickness of the front lead screens
should be selected with care to avoid excessive filtration in the
radiography of thin or light alloy materials, particularly at the
lower kilovoltages. In general, there is no exposure advantage
to the use of 0.005 in. in front and back lead screens below 125
kV in the radiography of 1⁄4-in. (6.35-mm) or lesser thickness
steel. As the kilovoltage is increased to penetrate thicker
sections of steel, however, there is a significant exposure
advantage. In addition to intensifying action, the back lead
screens are used as protection against back-scattered radiation
(see Section 12) and their thickness is only important for this
function. As exposure energy is increased to penetrate greater
thicknesses of a given subject material, it is customary to
increase lead screen thickness. For radiography using radioactive sources, the minimum thickness of the front lead screen
should be 0.005 in. (0.13 mm) for iridium-192, and 0.010 in.
(0.25 mm) for cobalt-60.
13.2 Other Metallic Screen Materials:
13.2.1 Lead oxide screens perform in a similar manner to
lead foil screens except that their equivalence in lead foil
thickness approximates 0.0005 in. (0.013 mm).
13.2.2 Copper screens have somewhat less absorption and
intensification than lead screens, but may provide somewhat
better radiographic sensitivity with higher energy above 1 MV.
14. Radiographic Image Quality
14.1 Radiographic image quality is a qualitative term used
to describe the capability of a radiograph to show flaws in the
area under examination. There are three fundamental components of radiographic image quality as shown in Fig. 1. Each
component is an important attribute when considering a
specific radiographic technique or application and will be
briefly discussed below.
14.2 Radiographic contrast between two areas of a radiograph is the difference between the film densities of those
areas. The degree of radiographic contrast is dependent upon
both subject contrast and film contrast as illustrated in Fig. 1.
14.2.1 Subject contrast is the ratio of X-ray or gamma-ray
intensities transmitted by two selected portions of a specimen.
Subject contrast is dependent upon the nature of the specimen
(material type and thickness), the energy (spectral composition,
hardness or wavelengths) of the radiation used and the intensity
and distribution of scattered radiation. It is independent of
time, milliamperage or source strength (curies), source distance
and the characteristics of the film system.
14.2.2 Film contrast refers to the slope (steepness) of the
film system characteristic curve. Film contrast is dependent
upon the type of film, the processing it receives and the amount
of film density. It also depends upon whether the film was
exposed with lead screens (or without) or with fluorescent
screens. Film contrast is independent, for most practical
purposes, of the wavelength and distribution of the radiation
reaching the film and, hence is independent of subject contrast.
For further information, consult Test Method E1815.
14.3 Film system granularity is the objective measurement
of the local density variations that produce the sensation of
graininess on the radiographic film (for example, measured
with a densitometer with a small aperture of # 0.0039 in. (0.1
mm)). Graininess is the subjective perception of a mottled
random pattern apparent to a viewer who sees small local
density variations in an area of overall uniform density (that is,
the visual impression of irregularity of silver deposit in a
processed radiograph). The degree of granularity will not affect
the overall spatial radiographic resolution (expressed in line
pairs per mm, etc.) of the resultant image and is usually
independent of exposure geometry arrangements. Granularity
section and by placing lead behind the film. In some cases
either or both the back lead screen and the lead contained in the
back of the cassette or film holder will furnish adequate
protection against back-scattered radiation. In other instances,
this must be supplemented by additional lead shielding behind
the cassette or film holder.
12.2 If there is any question about the adequacy of protection from back-scattered radiation, a characteristic symbol
(frequently a 1⁄8-in. (3.2-mm) thick letter B) should be attached
to the back of the cassette or film holder, and a radiograph
made in the normal manner. If the image of this symbol
appears on the radiograph as a lighter density than background,
it is an indication that protection against back-scattered radiation is insufficient and that additional precautions must be
taken.
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Radiographic Image Quality
Radiographic Contrast
Film System
Granularity
Subject
Contrast
Film
Contrast
Affected by:
• Absorption
differences
in specimen
(thickness,
composition,
density)
• Radiation
wavelength
• Scattered
radiation
Affected by:
• Type
of film
• Degree of
development
(type of
developer,
time,
temperature
and activity
of developer,
degree of
agitation)
• Film density
• Type of
screens (that is,
fluorescent,
lead or none)
Reduced or
enhanced by:
• Masks and
diaphragms
• Filters
• Lead screens
• Potter-Bucky
diaphragms
• Grain size and
distribution
within the
film emulsion
• Processing
conditions
(type and activity
of developer,
temperature
of developer,
etc.)
• Type of
screens (that is,
fluorescent,
lead or none)
• Radiation
quality (that is,
energy level,
filtration, etc.
• Exposure
quanta (that is,
intensity, dose,
etc.)
Radiographic Definition
Inherent
Unsharpness
Geometric
Unsharpness
Affected by:
• Degree of
screen-film
contact
• Total film
thickness
• Single or
double emulsion
coatings
• Radiation
quality
• Type and
thickness
of screens
(fluorescent,
lead or none)
Affected by:
• Focal spot
or source
physical size
• Source-to-film
distance
• Specimento-film
distance
• Abruptness of
thickness
changes in
specimen
• Motion of
specimen or
radiation
source
FIG. 1 Variables of Radiographic Image Quality
is affected by the applied screens, screen-film contact and film
processing conditions. For further information on detailed
perceptibility, consult Test Method E1815.
14.4 Radiographic definition refers to the sharpness of the
image (both the image outline as well as image detail).
Radiographic definition is dependent upon the inherent unsharpness of the film system and the geometry of the radiographic exposure arrangement (geometric unsharpness) as
illustrated in Fig. 1.
14.4.1 Inherent unsharpness (Ui) is the degree of visible
detail resulting from geometrical aspects within the film-screen
system, that is, screen-film contact, screen thickness, total
thickness of the film emulsions, whether single or doublecoated emulsions, quality of radiation used (wavelengths, etc.)
and the type of screen. Inherent unsharpness is independent of
exposure geometry arrangements.
14.4.2 Geometric unsharpness (Ug) determines the degree
of visible detail resultant from an “in-focus” exposure arrangement consisting of the source-to-film-distance, object-to-filmdistance and focal spot size. Fig. 2(a) illustrates these conditions. Geometric unsharpness is given by the equation:
Ug 5 Ft/do
where:
Ug =
F
=
t
=
do =
(1)
geometric unsharpness,
maximum projected dimension of radiation source,
distance from source side of specimen to film, and
source-object distance.
NOTE 3—do and t must be in the same units of measure; the units of Ug
will be in the same units as F.
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NOTE 4—A nomogram for the determination of Ug is given in Fig. 3
(inch-pound units). Fig. 4 represents a nomogram in metric units.
Example:
Given:
Source-object distance (do) = 40 in.,
Source size (F) = 500 mils, and
Source side of specimen to film distance (t) = 1.5 in.
Draw a straight line (dashed in Fig. 3) between 500 mils on the F scale and
1.5 in. on the t scale. Note the point on intersection (P) of this line with
the pivot line. Draw a straight line (solid in Fig. 3) from 40 in. on the do
scale through point P and extend to the Ug scale. Intersection of this line
with the Ug scale gives geometrical unsharpness in mils, which in the
example is 19 mils.
Inasmuch as the source size, F, is usually fixed for a given
radiation source, the value of Ug is essentially controlled by the
simple do/t ratio.
Geometric unsharpness (Ug) can have a significant effect on
the quality of the radiograph; therefore source-to-film-distance
(SFD) selection is important. The geometric unsharpness (Ug)
equation, Eq 1, is for information and guidance and provides a
means for determining geometric unsharpness values. The
amount or degree of unsharpness should be minimized when
establishing the radiographic technique.
15. Radiographic Distortion
15.1 The radiographic image of an object or feature within
an object may be larger or smaller than the object or feature
itself, because the penumbra of the shadow is rarely visible in
a radiograph. Therefore, the image will be larger if the object
or feature is larger than the source of radiation, and smaller if
object or feature is smaller than the source. The degree of
reduction or enlargement will depend on the source-to-object
E94 – 04 (2010)
FIG. 2 Effects of Object-Film Geometry
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FIG. 3 Nomogram for Determining Geometrical Unsharpness (Inch-Pound Units)
and object-to-film distances, and on the relative sizes of the
source and the object or feature (Fig. 2(b) and (c)).
15.2 The direction of the central beam of radiation should
be perpendicular to the surface of the film whenever possible.
The object image will be distorted if the film is not aligned
perpendicular to the central beam. Different parts of the object
image will be distorted different amount depending on the
extent of the film to central beam offset (Fig. 2(d)).
16. Exposure Calculations or Charts
16.1 Development or procurement of an exposure chart or
calculator is the responsibility of the individual laboratory.
16.2 The essential elements of an exposure chart or calculator must relate the following:
16.2.1 Source or machine,
16.2.2 Material type,
16.2.3 Material thickness,
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16.2.4
16.2.5
16.2.6
16.2.7
Film type (relative speed),
Film density, (see Note 5),
Source or source to film distance,
Kilovoltage or isotope type,
NOTE 5—For detailed information on film density and density measurement calibration, see Practice E1079.
16.2.8 Screen type and thickness,
16.2.9 Curies or milliampere/minutes,
16.2.10 Time of exposure,
16.2.11 Filter (in the primary beam),
16.2.12 Time-temperature development for hand processing; access time for automatic processing; time-temperature
development for dry processing, and
16.2.13 Processing chemistry brand name, if applicable.
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FIG. 4 Nomogram for Determining Geometrical Unsharpness (Metric Units)
16.3 The essential elements listed in 16.2 will be accurate
for isotopes of the same type, but will vary with X-ray
equipment of the same kilovoltage and milliampere rating.
16.4 Exposure charts should be developed for each X-ray
machine and corrected each time a major component is
replaced, such as the X-ray tube or high-voltage transformer.
16.5 The exposure chart should be corrected when the
processing chemicals are changed to a different manufacturer’s
brand or the time-temperature relationship of the processor
may be adjusted to suit the exposure chart. The exposure chart,
when using a dry processing method, should be corrected
based upon the time-temperature changes of the processor.
17. Technique File
17.1 It is recommended that a radiographic technique log or
record containing the essential elements be maintained.
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17.2 The radiographic technique log or record should contain the following:
17.2.1 Description, photo, or sketch of the test object
illustrating marker layout, source placement, and film location.
17.2.2 Material type and thickness,
17.2.3 Source to film distance,
17.2.4 Film type,
17.2.5 Film density, (see Note 5),
17.2.6 Screen type and thickness,
17.2.7 Isotope or X-ray machine identification,
17.2.8 Curie or milliampere minutes,
17.2.9 IQI and shim thickness,
17.2.10 Special masking or filters,
17.2.11 Collimator or field limitation device,
17.2.12 Processing method, and
17.2.13 View or location.
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17.3 The recommendations of 17.2 are not mandatory, but
are essential in reducing the overall cost of radiography, and
serve as a communication link between the radiographic
interpreter and the radiographic operator.
18. Penetrameters (Image Quality Indicators)
18.1 Practices E747, E801, E1025, and E1742 should be
consulted for detailed information on the design, manufacture
and material grouping of IQI’s. Practice E801 addresses IQI’s
for examination of electronic devices and provides additional
details for positioning IQI’s, number of IQI’s required, and so
forth.
18.2 Test Methods E746 and E1735 should be consulted for
detailed information regarding IQI’s which are used for determining relative image quality response of industrial film. The
IQI’s can also be used for measuring the image quality of the
radiographic system or any component of the systems equivalent penetrameter sensitivity (EPS) performance.
18.2.1 An example for determining and EPS performance
evaluation of several X-ray machines is as follows:
18.2.1.1 Keep the film and film processing parameters
constant, and take multiple image quality exposures with all
machines being evaluated. The machines should be set for a
prescribed exposure as stated in the standard and the film
density equalized. By comparison of the resultant films, the
relative EPS variations between the machines can be determined.
18.2.2 Exposure condition variables may also be studied
using this plaque.
18.2.3 While Test Method E746 plaque can be useful in
quantifying relative radiographic image quality, these other
applications of the plaque may be useful.
19. Identification of and Location Markers on
Radiographs
19.1 Identification of Radiographs:
19.1.1 Each radiograph must be identified uniquely so that
there is a permanent correlation between the part radiographed
and the film. The type of identification and method by which
identification is achieved shall be as agreed upon between the
customer and inspector.
19.1.2 The minimum identification should at least include
the following: the radiographic facility’s identification and
name, the date, part number and serial number, if used, for
unmistakable identification of radiographs with the specimen.
The letter R should be used to designate a radiograph of a
repair area, and may include − 1, − 2, etc., for the number of
repair.
19.2 Location Markers:
19.2.1 Location markers (that is, lead or high-atomic number metals or letters that are to appear as images on the
radiographic film) should be placed on the part being examined, whenever practical, and not on the cassette. Their exact
locations should also be marked on the surface of the part being
radiographed, thus permitting the area of interest to be located
accurately on the part, and they should remain on the part
during radiographic inspection. Their exact location may be
permanently marked in accordance with the customer’s requirements.
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19.2.2 Location markers are also used in assisting the
radiographic interpreter in marking off defective areas of
components, castings, or defects in weldments; also, sorting
good and rejectable items when more than one item is
radiographed on the same film.
19.2.3 Sufficient markers must be used to provide evidence
on the radiograph that the required coverage of the object being
examined has been obtained, and that overlap is evident,
especially during radiography of weldments and castings.
19.2.4 Parts that must be identified permanently may have
the serial numbers or section numbers, or both, stamped or
written upon them with a marking pen with a special indelible
ink, engraved, die stamped, or etched. In any case, the part
should be marked in an area not to be removed in subsequent
fabrication. If die stamps are used, caution is required to
prevent breakage or future fatigue failure. The lowest stressed
surface of the part should be used for this stamping. Where
marking or stamping of the part is not permitted for some
reason, a marked reference drawing or shooting sketch is
recommended.
20. Storage of Film
20.1 Unexposed films should be stored in such a manner
that they are protected from the effects of light, pressure,
excessive heat, excessive humidity, damaging fumes or vapors,
or penetrating radiation. Film manufacturers should be consulted for detailed recommendations on film storage. Storage
of film should be on a “first in,” “first out” basis.
20.2 More detailed information on film storage is provided
in Guide E1254.
21. Safelight Test
21.1 Films should be handled under safelight conditions in
accordance with the film manufacturer’s recommendations.
ANSI PH2.22 can be used to determine the adequacy of
safelight conditions in a darkroom.
22. Cleanliness and Film Handling
22.1 Cleanliness is one of the most important requirements
for good radiography. Cassettes and screens must be kept
clean, not only because dirt retained may cause exposure or
processing artifacts in the radiographs, but because such dirt
may also be transferred to the loading bench, and subsequently
to other film or screens.
22.2 The surface of the loading bench must be kept clean.
Where manual processing is used cleanliness will be promoted
by arranging the darkroom with processing facilities on one
side and film-handling facilities on the other. The darkroom
will then have a wet side and a dry side and the chance of
chemical contamination of the loading bench will be relatively
slight.
22.3 Films should be handled only at their edges, and with
dry, clean hands to avoid finger marks on film surfaces.
22.4 Sharp bending, excessive pressure, and rough handling
of any kind must be avoided.
23. Film Processing, General
23.1 To produce a satisfactory radiograph, the care used in
making the exposure must be followed by equal care in
E94 – 04 (2010)
processing. The most careful radiographic techniques can be
nullified by incorrect or improper darkroom procedures.
23.2 Sections 24-26 provide general information for film
processing. Detailed information on film processing is provided in Guide E999.
24. Automatic Processing
24.1 Automatic Processing—The essence of the automatic
processing system is control. The processor maintains the
chemical solutions at the proper temperature, agitates and
replenishes the solutions automatically, and transports the films
mechanically at a carefully controlled speed throughout the
processing cycle. Film characteristics must be compatible with
processing conditions. It is, therefore, essential that the recommendations of the film, processor, and chemical manufacturers
be followed.
24.2 Automatic Processing, Dry—The essence of dry automatic processing is the precise control of development time
and temperature which results in reproducibility of radiographic density. Film characteristics must be compatible with
processing conditions. It is, therefore, essential that the recommendations of the film and processor manufacturers be followed.
25. Manual Processing
25.1 Film and chemical manufacturers should be consulted
for detailed recommendations on manual film processing. This
section outlines the steps for one acceptable method of manual
processing.
25.2 Preparation—No more film should be processed than
can be accommodated with a minimum separation of 1⁄2 in.
(12.7 mm). Hangers are loaded and solutions stirred before
starting development.
25.3 Start of Development—Start the timer and place the
films into the developer tank. Separate to a minimum distance
of 1⁄2 in. (12.7 mm) and agitate in two directions for about 15
s.
25.4 Development—Normal development is 5 to 8 min at
68°F (20°C). Longer development time generally yields faster
film speed and slightly more contrast. The manufacturer’s
recommendation should be followed in choosing a development time. When the temperature is higher or lower, development time must be changed. Again, consult manufacturerrecommended development time versus temperature charts.
Other recommendations of the manufacturer to be followed are
replenishment rates, renewal of solutions, and other specific
instructions.
25.5 Agitation—Shake the film horizontally and vertically,
ideally for a few seconds each minute during development.
This will help film develop evenly.
25.6 Stop Bath or Rinse—After development is complete,
the activity of developer remaining in the emulsion should be
neutralized by an acid stop bath or, if this is not possible, by
rinsing with vigorous agitation in clear water. Follow the film
manufacturer’s recommendation of stop bath composition (or
length of alternative rinse), time immersed, and life of bath.
25.7 Fixing—The films must not touch one another in the
fixer. Agitate the hangers vertically for about 10 s and again at
the end of the first minute, to ensure uniform and rapid fixation.
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Keep them in the fixer until fixation is complete (that is, at least
twice the clearing time), but not more than 15 min in relatively
fresh fixer. Frequent agitation will shorten the time of fixation.
25.8 Fixer Neutralizing—The use of a hypo eliminator or
fixer neutralizer between fixation and washing may be advantageous. These materials permit a reduction of both time and
amount of water necessary for adequate washing. The recommendations of the manufacturers as to preparation, use, and
useful life of the baths should be observed rigorously.
25.9 Washing—The washing efficiency is a function of
wash water, its temperature, and flow, and the film being
washed. Generally, washing is very slow below 60°F (16°C).
When washing at temperatures above 85°F (30°C), care should
be exercised not to leave films in the water too long. The films
should be washed in batches without contamination from new
film brought over from the fixer. If pressed for capacity, as
more films are put in the wash, partially washed film should be
moved in the direction of the inlet.
25.9.1 The cascade method of washing uses less water and
gives better washing for the same length of time. Divide the
wash tank into two sections (may be two tanks). Put the films
from the fixer in the outlet section. After partial washing, move
the batch of film to the inlet section. This completes the wash
in fresh water.
25.9.2 For specific washing recommendations, consult the
film manufacturer.
25.10 Wetting Agent—Dip the film for approximately 30 s
in a wetting agent. This makes water drain evenly off film
which facilitates quick, even drying.
25.11 Residual Fixer Concentrations— If the fixing chemicals are not removed adequately from the film, they will in time
cause staining or fading of the developed image. Residual fixer
concentrations permissible depend upon whether the films are
to be kept for commercial purposes (3 to 10 years) or must be
of archival quality. Archival quality processing is desirable for
all radiographs whenever average relative humidity and temperature are likely to be excessive, as is the case in tropical and
subtropical climates. The method of determining residual fixer
concentrations may be ascertained by reference to ANSI
PH4.8, PH1.28, and PH1.41.
25.12 Drying—Drying is a function of (1) film (base and
emulsion); (2) processing (hardness of emulsion after washing,
use of wetting agent); and (3) drying air (temperature, humidity, flow). Manual drying can vary from still air drying at
ambient temperature to as high as 140°F (60°C) with air
circulated by a fan. Film manufacturers should again be
contacted for recommended drying conditions. Take precaution
to tighten film on hangers, so that it cannot touch in the dryer.
Too hot a drying temperature at low humidity can result in
uneven drying and should be avoided.
26. Testing Developer
26.1 It is desirable to monitor the activity of the radiographic developing solution. This can be done by periodic
development of film strips exposed under carefully controlled
conditions, to a graded series of radiation intensities or time, or
by using a commercially available strip carefully controlled for
film speed and latent image fading.
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27. Viewing Radiographs
27.1 Guide E1390 provides detailed information on requirements for illuminators. The following sections provide general
information to be considered for use of illuminators.
27.2 Transmission—The illuminator must provide light of
an intensity that will illuminate the average density areas of the
radiographs without glare and it must diffuse the light evenly
over the viewing area. Commercial fluorescent illuminators are
satisfactory for radiographs of moderate density; however, high
light intensity illuminators are available for densities up to 3.5
or 4.0. Masks should be available to exclude any extraneous
light from the eyes of the viewer when viewing radiographs
smaller than the viewing port or to cover low-density areas.
27.3 Reflection—Radiographs on a translucent or opaque
backing may be viewed by reflected light. It is recommended
that the radiograph be viewed under diffuse lighting conditions
to prevent excess glare. Optical magnification can be used in
certain instances to enhance the interpretation of the image.
28. Viewing Room
28.1 Subdued lighting, rather than total darkness, is preferable in the viewing room. The brightness of the surroundings
should be about the same as the area of interest in the
radiograph. Room illumination must be so arranged that there
are no reflections from the surface of the film under examination.
29. Storage of Processed Radiographs
29.1 Guide E1254 provides detailed information on controls
and maintenance for storage of radiographs and unexposed
film. The following sections provide general information for
storage of radiographs.
29.2 Envelopes having an edge seam, rather than a center
seam, and joined with a nonhygroscopic adhesive, are preferred, since occasional staining and fading of the image is
caused by certain adhesives used in the manufacture of
envelopes (see ANSI PH1.53).
30. Records
30.1 It is recommended that an inspection log (a log may
consist of a card file, punched card system, a book, or other
record) constituting a record of each job performed, be
maintained. This record should comprise, initially, a job
number (which should appear also on the films), the identification of the parts, material or area radiographed, the date the
films are exposed, and a complete record of the radiographic
procedure, in sufficient detail so that any radiographic techniques may be duplicated readily. If calibration data, or other
records such as card files or procedures, are used to determine
the procedure, the log need refer only to the appropriate data or
other record. Subsequently, the interpreter’s findings and
disposition (acceptance or rejection), if any, and his initials,
should also be entered for each job.
31. Reports
31.1 When written reports of radiographic examinations are
required, they should include the following, plus such other
items as may be agreed upon:
31.1.1 Identification of parts, material, or area.
31.1.2 Radiographic job number.
31.1.3 Findings and disposition, if any. This information can
be obtained directly from the log.
32. Identification of Completed Work
32.1 Whenever radiography is an inspective (rather than
investigative) operation whereby material is accepted or rejected, all parts and material that have been accepted should be
marked permanently, if possible, with a characteristic identifying symbol which will indicate to subsequent or final
examiners the fact of radiographic acceptance.
32.2 Whenever possible, the completed radiographs should
be kept on file for reference. The custody of radiographs and
the length of time they are preserved should be agreed upon
between the contracting parties.
33. Keywords
33.1 exposure calculations; film system; gamma-ray; image
quality indicator (IQI); radiograph; radiographic examination;
radiographic quality level; technique file; X-ray
APPENDIX
(Nonmandatory Information)
X1. USE OF FLUORESCENT SCREENS
X1.1 Description—Fluorescent intensifying screens have a
cardboard or plastic support coated with a uniform layer of
inorganic phosphor (crystalline substance). The support and
phosphor are held together by a radiotransparent binding
material. Fluorescent screens derive their name from the fact
that their phosphor crystals “fluoresce” (emit visible light)
when struck by X or gamma radiation. Some phosphors like
calcium tungstate (CaWO4) give off blue light while others
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known as rare earth emit light green.
X1.2 Purpose and Film Types—Fluorescent screen exposures are usually much shorter than those made without screens
or with lead intensifying screens, because radiographic films
generally are more responsive to visible light than to direct
X-radiation, gamma radiation, and electrons.
E94 – 04 (2010)
X1.2.1 Films fall into one of two categories: non-screen
type film having moderate light response, and screen type film
specifically sensitized to have a very high blue or green light
response. Fluorescent screens can reduce conventional exposures by as much as 150 times, depending on film type.
X1.3 Image Quality and Use—The image quality associated with fluorescent screen exposures is a function of sharpness, mottle, and contrast. Screen sharpness depends on phosphor crystal size, thickness of the crystal layer, and the
reflective base coating. Each crystal emits light relative to its
size and in all directions thus producing a relative degree of
image unsharpness. To minimize this unsharpness, screen to
film contact should be as intimate as possible. Mottle adversely
affects image quality in two ways. First, a “quantum” mottle is
dependent upon the amount of X or gamma radiation actually
absorbed by the fluorescent screen, that is, faster screen/film
systems lead to greater mottle and poorer image quality. A“
structural” mottle, which is a function of crystal size, crystal
uniformity, and layer thickness, is minimized by using screens
having small, evenly spaced crystals in a thin crystalline layer.
Fluorescent screens are highly sensitive to longer wavelength
scattered radiation. Consequently, to maximize contrast when
this non-image forming radiation is excessive, fluorometallic
intensifying screens or fluorescent screens backed by lead
screens of appropriate thickness are recommended. Screen
technology has seen significant advances in recent years, and
today’s fluorescent screens have smaller crystal size, more
uniform crystal packing, and reduced phosphor thickness. This
translates into greater screen/film speed with reduced unsharpness and mottle. These improvements can represent some
meaningful benefits for industrial radiography, as indicated by
the three examples as follows:
X1.3.1 Reduced Exposure (Increased Productivity)—There
are instances when prohibitively long exposure times make
conventional radiography impractical. An example is the inspection of thick, high atomic number materials with low curie
isotopes. Depending on many variables, exposure time may be
reduced by factors ranging from 23 to 1053 when the
appropriate fluorescent screen/film combination is used.
X1.3.2 Improved Safety Conditions (Field Sites)—Because
fluorescent screens provide reduced exposure, the length of
time that non-radiation workers must evacuate a radiographic
inspection site can be reduced significantly.
X1.3.3 Extended Equipment Capability—Utilizing the
speed advantage of fluorescent screens by translating it into
reduced energy level. An example is that a 150 kV X-ray tube
may do the job of a 300 kV tube, or that iridium 192 may be
used in applications normally requiring cobalt 60. It is possible
for overall image quality to be better at the lower kV with
fluorescent screens than at a higher energy level using lead
screens.
BIBLIOGRAPHY ON INDUSTRIAL RADIOGRAPHY
For conciseness, this bibliography has been limited to books and specifically to books in English published after 1950.
(1) Clark, G. L., Applied X-Rays, 4th ed., McGraw Hill Book Co.,
Inc., New York, 1955.
(2) Clauser, H. R., Practical Radiography for Industry, Reinhold
Publishing Corp., New York, 1952.
(3) Hogarth, C. A., and Blitz, J. (Editors), Techniques of Nondestructive Testing, Butte Worth and Co., Ltd., London, 1960.
(4) McMaster, R. C. (Editor), Nondestructive Testing Handbook, The
Ronald Press, New York, 1960.
(5) Morgan, R. H., and Corrigan, K. E. (Editors), Handbook of
Radiology, The Year Book Publishers, Inc., Chicago, 1955.
(6) Reed, M. E., Cobalt-60 Radiography in Industry, Tracer-lab, Inc.,
Boston, 1954.
(7) Robertson, J. K., Radiology Physics, 3rd ed., D. Van Nostrand
Company, New York, 1956.
(8) Weyl, C., and Warren, S. R., Radiologic Physics, 2nd ed., Charles
C. Thomas, Springfield, IL, 1951.
(9) Wilshire, W. J. (Editor), A Further Handbook of Industrial
Radiology, Edward Arnold and Company, London, 1957.
(10) McGonnagle, W. J., Nondestructive Testing, McGraw Hill Book
Co., Inc., New York, 1961.
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(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
Handbook on Radiography, Revised edition, Atomic Energy of
Canada Ltd. Ottawa, Ont., 1950.
Papers on Radiography, ASTM STP 96, ASTM, 1950.
Symposium on the Role of Nondestructive Testing in the Economics of Production, ASTM STP 112, ASTM, 1951.
Radioisotope Technique, Vol II, H. M. Stationery Office, London,
1952.
Symposium on Nondestructive Testing, ASTM STP 145, ASTM,
1953.
Memorandum on Gamma-Ray Sources for Radiography, Revised
edition, Institute of Physics, London, 1954.
Papers on Nondestructive Testing, see Proceedings, ASTM, Vol
54, 1954.
Radiography in Modern Industry (3rd edition), Eastman Kodak
Co., Rochester, NY, 1969.
Symposium on Nondestructive Tests in the Field of Nuclear
Energy, ASTM STP 223, ASTM, 1958.
Radiographer’s Reference (3rd edition), E. I. du Pont de Nemours
& Co., Inc., Wilmington, DE, 1974 (or latest revision).
E94 – 04 (2010)
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